InPouch TV TM culture for detection of Trichomonas vaginalis

Transcription

1 Indian J Med Res 125, April 2007, pp InPouch TV TM culture for detection of Trichomonas vaginalis Seema Sood, Srujana Mohanty, Arti Kapil, Jorge Tolosa + & Suneeta Mittal* Departments of Microbiology, *Obstetrics & Gynaecology, All India Institute of Medical Sciences, New Delhi, India & + Global Network for Perinatal & Reproductive Health, Thomas Jefferson University, Philadelphia, PA, USA Received March 29, 2006 Background & objectives: Trichomonas vaginalis accounts for almost half of all curable sexually transmitted infections and has also been associated with adverse outcomes of pregnancy and increased risk of HIV in women. Diagnosis of the condition by direct wet mount examination has a low sensitivity. Herein, we describe our experience with InPouch culture system for the detection of T. vaginalis. Methods: This prospective study was carried out from May 2003 to April 2004 among women presenting with genitourinary symptoms attending a primary health center clinic in Ballabhgarh, India. Two vaginal swabs (cotton tips) were obtained from each woman. The first swab was obtained from the lateral wall of vagina and was used to make a wet mount preparation. The second swab was obtained from the posterior fornix of the vagina and inoculated in the InPouch for culture of T. vaginalis. Results: Of the 601 women, 22 were positive by direct microscopy for T. vaginalis while 40 were positive by culture. Overall, T. vaginalis accounted for 6.7 per cent of reproductive tract infections. Interpretation & conclusion: The InPouch TV culture system is a simple, cost-effective and a sensitive method for diagnosing T. vaginalis and may be recommended for routine use in diagnosing genital tract infections. Key words InPouch culture - reproductive tract infections - sexually transmitted infections - Trichomonas vaginalis 567

2 568 INDIAN J MED RES, APRIL 2007 Trichomonas vaginalis, a sexually transmitted flagellated protozoan, afflicts an estimated 180 million women per year worldwide 1. The World Health Organization (WHO) has estimated that this infection accounts for almost half of all curable sexually transmitted infections 2. Clinical syndrome in females vary from asymptomatic presentations to (more commonly) vaginitis with copious discharge. Infection can be associated with serious sequelae such as preterm labour, premature rupture of membranes and low birth weight as well as increased risk of transmission of other sexually transmitted diseases (STDs), including human immunodeficiency virus (HIV) 3,4. Associations of trichomoniasis in women with adverse outcomes of pregnancy and increased risk of HIV suggest a need for increased control efforts, and accurate diagnosis is necessary for specific treatment and control of this disease. Diagnosis of trichomoniasis in women is usually accomplished via direct microscopic examination of the vaginal fluid by wet mount preparation; however, the sensitivity of this test is low (overall 60%) and may be lower in asymptomatic women. Culture is clearly the most sensitive diagnostic method and various culture media have been described for cultivation of T. vaginalis. Though polymerase chain reaction (PCR) techniques have been found more sensitive than culture, different studies have shown its specificity to be slightly lower than culture 5,6. In this study, we describe our experience with the InPouch culture system (Biomed Diagnostics, San Jose, California) for the detection of T. vaginalis. This is a commercially available system which combines a wet preparation and a culture method to detect T. vaginalis. Material & Methods We carried out a prospective study from May 2003 to April 2004 among women presenting with genitourinary symptoms attending a primary health center clinic in Ballabhgarh, Haryana, in India. An attempt was made to detect T. vaginalis infection in symptomatic women. Informed consent was obtained from each participant woman. The inclusion criteria for the study were, married and sexually active women between 18 to 49 yr of age with self-reported symptoms of vaginal discharge and/or genital itching and/or genital burning. Pregnant women, women with severe medical disorders requiring immediate referral to higher level of health care, women who were currently menstruating, never been sexually active, who had a hysterectomy, had taken a course of antibiotics within last three weeks and who had been previously enrolled in this study were excluded. This study was a part of a large collaboration study with USA. Two vaginal swabs (cotton tips) were obtained from each woman. The purpose was to get as much specimen as possible. The first swab was obtained from the lateral wall of vagina and was used to make a wet mount preparation on a glass slide with a drop of normal saline on the site of specimen collection. The slide was initially scanned at 100X, looking for motile trichomonads, and then at 400X to confirm motility, flagellar movement and morphologic features of the organisms. Negative wet mounts were examined for at least two minutes. The second swab was obtained from the posterior fornix of the vagina and inoculated in the top pouch of InPouch (Biomed Diagnostics, USA) for culture of T. vaginalis. InPouch TV is a double pouched container made of soft plastic (Fig.). The specimen was introduced into the bottom pouch immediately after collection; microscopic examination of the bottom pouch was conducted when the specimen arrived in the laboratory (no examination was made of the top pouch because its contents had been immediately pushed into the bottom pouch). The cultures were incubated at 35 o C and examined for motile T. vaginalis at 24, 48 and 96 h

3 SOOD et al: INPOUCH TV CULTURE 569 Top pouch Bottom pouch Opening for insertion of swab Fig. Diagram of InPouch TV. of incubation by using a 10X objective directly through the pouch. Internal quality control for T. vaginalis InPouch culture was made by incubating one InPouch per batch as a sterility check on reagents and inoculating one pouch with a known culture of T. vaginalis to check the quality of the batch of InPouch. Statistical analysis was done using the Mc-Nemar Chi Square test. Results & Discussion A total of 710 women were screened as they were willing to participate in the study, but only 611 were eligible for enrolment. However, data could be collected and analyzed from 601 women as the rest declined internal examination. Of the 601 women, 22 were positive by direct microscopy for T. vaginalis while 40 were positive by culture which was found to be statistically significant (P < 0.001). All were culture positive within 48 h of incubation. Overall, T. vaginalis accounted for 6.7 per cent (40/601) of reproductive tract infections. The time honoured approach for the diagnosis of trichomonal infection has been microscopic evaluation by the wet mount method, a procedure first described by Donne in This procedure, however, detects only 35 to 80 per cent of the cases, depending on the expertise of the microscopist 8,9. It is already established that a minimal concentration of 10 4 organisms per milliliter of vaginal fluid appears to be necessary for identification of the protozoa by wet mount 8. The relatively low sensitivity of wet mount examination has been confirmed in this study too. Because of the limitations of the wet mount, culture remains the most accurate single method for detecting the presence of T. vaginalis in patient samples Routinely, 95 per cent of cases are diagnosed by this method. Optimal growth and reproduction of T. vaginalis require anaerobic conditions and an unusually large number of essential nutrients, including carbohydrates, amino acids, purines, pyrimidines, fatty acids, vitamins and iron 11. Although several commercial liquid media are available for this purpose, Diamond s medium is considered the gold standard. The InPouch TV culture system, the one we have used has been found to be as reliable as Diamond s medium in detecting T. vaginalis 12. We observed that the InPouch TV culture detected 45 per cent more positives than the traditional wet mount. The sensitivity of wet mount preparation in our study was 55 per cent and falls very much within the range documented so far. The specificity of the wet mount preparation was 100 per cent. The presence of trichomonads was determined by its characteristic size, shape and mobility in both tests, the specificity was therefore considered the same for both the wet mount and the InPouch TV method.

4 570 INDIAN J MED RES, APRIL 2007 Overall, T. vaginalis accounted for 6.7 per cent of reproductive tract infections in our study. Worldwide, researchers have reported a prevalence of 1.3 to 16.5 per cent 13,14 of T. vaginalis in reproductive tract infections. The prevalence of T. vaginalis in India ranges from 0.8 to 14.0 per cent but most studies have relied on the wet preparation alone and there is no gold standard confirmation Although the combination of culture and wet mount examination remains the standard approach for detecting T. vaginalis in patient samples 12, InPouch offers some distinct advantages. Once the specimen is placed by a clinician into the InPouch chamber, microscopic observation can be made directly through the bag as the bag can be used as a slide on the stage of the microscope. This obviates the need for sampling to examine the culture for growth thereby preventing contamination. These can be conveniently transported from the site of collection to the laboratory and can be stored at room temperature. Other media, once prepared, require refrigeration. Further, its cost is comparable to the ordinary culture tube. Therefore, the InPouch culture system may be used as a routine method of diagnosing trichomoniasis. Acknowledgment Authors acknowledge the Global Network for Perinatal and Reproductive Health (GNPRH), USA, for providing the pouches, and cultures were done as a part of a study funded by Population Council, New Delhi, India. References 1. World Health Organization. Global prevalence and incidence of selected curable sexually transmitted infections, WHO/HIV-AIDS/ /CDC/CSR/EDC/ Cates W and the American Social Health Association Panel. Estimates of the incidence and prevalence of sexually transmitted diseases in the United States. Sex Transm Dis 1999; 26 : Wolner-Hanssen P, Krieger JN, Stevens CE, Kiviat NB, Koutsky L, Critchlow C, et al. Clinical manifestations of vaginal trichomoniasis. JAMA 1989; 261 : Royce RA, Seva A, Cates W, Cohen MS. Sexual transmission of HIV. N Engl J Med 1997; 336 : Madico G, Quinn TC, Rampalo A, McKee KT Jr, Gaydos CA. Diagnosis of Trichomonas vaginalis infection by PCR using vaginal swab samples. J Clin Microbiol 1998; 36 : Lawing L, Hedges S, Schwebke J. Detection of trichomoniasis in vaginal and urine specimens from women by culture and PCR. J Clin Microbiol 2000; 38 : Donne A. Animacules observes dans les mantieres purulentes at al produit des secretions des organs genitaux de Thomme et de la femme. CR Acad Sci 1836; 3 : Krieger JN, Tam MR, Stevens CE, Nielsen ID, Hale J, Kaviat NB, et al. Diagnosis of trichomoniasis: comparison of conventional wet-mount examination with cytologic studies, cultures, and monoclonal antibody staining of direct specimens. JAMA 1988; 259 : McMillan A. Laboratory diagnostic methods and cryopreservation of trichomonads. In: Honigsberg BM, editor. Trichomonads parasitic in humans. New York: Springer; 1989 p Spence MR, Hollander DH, Smith J, Mc Gaig L, Sewell P, Brockman M. The clinical and laboratory diagnosis of Trichomonas vaginalis infection. Sex Transm Dis 1980; 7 : Linstead D. Cultivation. In: Honigsberg BM, editor. Trichomonads parasitic in humans. New York: Springer; 1989 p Levi MH, Torres J, Pina C, Klein RS. Comparison of the InPouch TV culture system and Diamond s modified medium for detection of Trichomonas vaginalis. J Clin Microbiol 1997; 35 : Anh PK, Khauh NT, Ha DT, Chien do T, Thue PT, Luong PH, et al. Prevalence of lower genital tract infection among women attending maternal and child health and family planning clinics in Hanoi, Vietnam. Southeast Asian J Trop Med Public Health 2003; 34 :

5 SOOD et al: INPOUCH TV CULTURE Garcia PJ, Chavez S, Feringa B, Chiappe M, Li W, Jansen KW, et al. Reproductive tract infections in rural women from the highlands, jungle and coastal regions of Peru. Bull World Health Organ 2004; 82 : AIDS Prevention and Control Project (APAC) Community prevalence of sexually transmitted diseases in Tamil Nadu A Report. AIDS Prevention and Control Project, Voluntary Health Services, Chennai, India. 16. Kumar P, Sharma NK, Sharma U, Sharma RP, Idnani R, Agarwal AK. Trichomoniasis and candidiasis in cohorts of females with vaginal discharge. Indian J Sex Transm Dis 1990; 11 : Bang RA, Bang AT, Baitule M, Choudhary Y, Sarmukaddam S, Tale O. High prevalence of gynaecological diseases in rural Indian women. Lancet 1989; 8629 : Reprint requests: Dr Suneeta Mittal, Professor & Head, Department of Obstetrics & Gynaecology Reprint requests: All India Institute of Medical Sciences, Ansari Nagar, New Delhi , India Reprint requests: suneeta_mittal@yahoo.com